ΔE 23.1, loose: different enough that you should pick on purpose. A-28M Greyish Blue is a little darker, much more muted, cooler than Ghoul Green.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 23). A-28M Greyish Blue is a little darker, much more muted, cooler than Ghoul Green.
The same difference applies the other way round: Ghoul Green is a little lighter, much more saturated, warmer.
ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.
See Ghoul Green on the colour wheel See A-28M Greyish Blue on the colour wheel
All matches: Ghoul Green equivalents · A-28M Greyish Blue equivalents